1. Field of the Invention
This invention relates to a novel substituted thiadiazole which possesses herbicidal activity, in particular, activity as a selective herbicide in sugarcane and citrus. The invention also relates to a method for controlling unwanted vegetation using the compound, and to herbicidal compositions containing the compound.
2. Description of the Prior Art
While the prior art refers to many thiadiazoles and derivatives thereof, none of the prior art teaches the unexpected herbicidal selectivity against sugarcane and citrus demonstrated by the compound disclosed and claimed herein.
In the prior art, British Pat. No. 1,195,672 (published June 17, 1970), discloses and claims thiadiazolylureas, including compounds having a haloalkyl substituent at the 5-position of the thiadiazole ring. The compounds are alleged to be active both as pre- and postemergent herbicides.
Also in the prior art is British Pat. No. 1,266,172 (published Mar. 8, 1972), which discloses and claims thiadiazolylureas having an acyclic hydrocarbon radical or a halogenated derivative thereof at the 5-position of the thiadiazole ring. These disclosed thiadiazolylureas are alleged to have utility as agricultural chemicals, that is, they are active as herbicides, plant fungicides, insecticides, and/or acaricides. When used as herbicides, the compounds are alleged to be active when applied either preemergence or postemergence. Some of the compounds may be applied to weeds or crops for defoliation or dessication, and others are suitable for use in herbicidal soil sterilant applications.
Yet another prior art reference is British Patent Application No. 1,276,925 (published June 7, 1972), which is directed to 1,3,4-thiadiazolylureas substituted in the 5-position of the thiadiazole ring with haloalkyl or trifluoroalkoxyalkyl groups, to a process for producing the compounds, and to their use as herbicides. The compounds are alleged to exhibit a good selectivity when applied either pre- or postemergence in cotton, and in cereals such as wheat and oats.
Still another prior art reference is U.S. Pat. No. 3,937,715 (Feb. 10, 1976), which reference is directed to 2-(tetrahaloethyl)-5-amino-1,3,4-thia- or oxadiazoles and their salts, alleged to be active as plant growth regulators and herbicides, and alleged to be especially valuable for dwarfing barley. The compounds of the reference bear a 1,1-difluoro-2,3-dichloroethyl substituent at the 5-position of the thiadiazole ring.
Also in the prior art is U.S. Pat. No. 4,097,264 (June 27, 1978), which discloses thiadiazolylureas substituted in the 5-position with a monochloro or di-chloro-t-butyl moiety. The compounds are alleged to be useful in herbicidal compositions and methods for controlling unwanted vegetation by pre- or postemergent application.